What is the clinical evidence from this study?

Study design: Cross-Sectional. Population: Congestive Heart Failure (n=1739). Intervention: Estimated Glomerular Filtration Rate (eGFR) and CHF status. Primary outcome: Association of BNP levels with eGFR and presence or absence of CHF (p=<0.001).

November 17, 2009Clinical Medicine & Research31 citationsOpen Access

Association of B-Type Natriuretic Peptide Levels With Estimated Glomerular Filtration Rate and Congestive Heart Failure

Q: What are the key findings of this study?

B-Type natriuretic peptide (BNP) levels demonstrated a strong inverse association with estimated glomerular filtration rate in both CHF and non-CHF patients (P<0.001).

CWCarmen WileyProvidence Sacred Heart Medical Center SSS. P. SwitzerSt. Cloud VA Health Care System RBRichard L. BergMarshfield Clinic

Key Result

B-Type natriuretic peptide (BNP) levels demonstrated a strong inverse association with estimated glomerular filtration rate in both CHF and non-CHF patients (P<0.001).

Study Design

Type

Cross-Sectional (n=1,739)

Structured PICO

Population

The provided text contains two distinct studies: 1) 1,739 patients with a BNP level and serum creatinine measurement on the same day (537 with CHF, 1,202 without CHF). 2) 472 residents of the Marshfield Epidemiologic Study Area (MESA) with their first ever episode of atrial flutter (AFL, n=76) or atrial fibrillation (AF, n=396).

Outcome

Study 1: Association of BNP levels with estimated glomerular filtration rate (eGFR) and congestive heart failure (CHF). Study 2: Differences in comorbidities (COPD, CHF, hypertension, etc.) present at the time of initial diagnosis of AFL versus AF.

Main Result

p-value: p=<0.001

Limitations

Inability to account for severity of illness in COPD, CHF, and hypertension
Small sample size
Echocardiographic parameters were not evaluated
Population is predominantly white and rural

Abstract

BACKGROUND: The causes of elevated B-Type natriuretic peptide (BNP) levels are multifactorial. Renal dysfunction has been shown to affect BNP levels in some studies and the diagnostic value of BNP levels in the presence of chronic kidney disease has been questioned. Prior studies have involved small patient populations with variable outcomes noted. This study evaluated the association of BNP levels with an estimated glomerular filtration rate (eGFR) and presence or absence of congestive heart failure (CHF). METHODS: A retrospective, cross-sectional study in which medical records were electronically screened, identified patients with a BNP level and serum creatinine measurement on the same day between December 2002 and March 2006. RESULTS: Of 1739 eligible patients, 537 were positive for CHF and 1202 were negative for CHF by our criteria. There was a clear trend for BNP to be higher with the advancement of CHF, as determined by New York Heart Association (NYHA) classification (P<0.001). Median BNP levels increased from 65 pg/mL in patients without CHF to 496 pg/mL in patients with NYHA class IV CHF (P <0.001), and there was a strong inverse association with eGFR (P <0.001). CONCLUSION: BNP levels show a strong inverse association with eGFR in both CHF and non-CHF patients. Currently best practice at most institutions involves use of BNP cutoff diagnostic levels not adjusted for eGFR. The data presented underlines that eGFR is a significant confounder of BNP measurement especially when renal status is compromised and interpretation of clinical significance in the presence of elevated BNP measures should take renal status into consideration.

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